If you like the demasoni you can keep him. Just get him 12-15 friends and get rid of all the other fish. You could also add 8 - 10 yellow labs and have a nice yellow, blue, and black combo in the tank.
Green Terrors and Venstus might work. Both fish could handle something in the high-7s. Another option if you want to build a tank around GTs would be to add some Silver dollars and another robust, but not too mean fish.